Q:
Is OmniWeb compatible with Mathematica files?
A:
The short answer is that OmniWeb handles Mathematica files just fine, as long as the server advertises the content type properly. For example right now, the server at www.ics.uci.edu claims /~eppstein/egypt.ma has a Content-Type of "text/plain", which is why OmniWeb displays it as text.
If you contact the webmaster, they should be able to fix their server. To see the file as a Mathematica file, you need to have the webmaster configure your server so it advertises ".ma" files with a MIME type of "application/mathematica". It looks like you're using the NCSA server, so this is done by editing the conf/mime.types file and adding the line:
application/mathematica ma